There is some good news. At Performance Plus the 355/65/18's are $291. each, and the 305-60-18's are $207. While it's probably not much consolation, the price you paid is an even better deal than you bargained for.

This is just a shot in the dark, but since there is a $80. or so price difference in your favor...maybe you can find a local tire company who carries Nitto and would do a trade?? Just a thought but even if you had to pay a little out of pocket for the trade and / or for mounting, that's still better than where you are now. If nothing else maybe you could pull off the trade and get the seller to refund anything you were out for the switch??

Good luck!